In order to make a commercially acceptable product, textile materials, such as tufted pile carpets, are typically dyed to a desirable color. The most common method used for dyeing textile materials is the vat dyeing process. The vat method is essentially a batch process wherein a quantity of textile material is added to a vat of hot dye. After sufficient time for complete penetration of the textile material by the dye, the material is removed from the vat and processed further in a steam chamber to assure complete fixation of the dye to the textile fibers. The carpet then must be washed extensively to remove all excess dye. Being a batch process, this method of dyeing is necessarily labor intensive. Furthermore, amounts of dye in excess of that necessary for dyeing the material are required and large quantities of water must be used to wash the excess dye out of the material. This washing process typically creates waste effluent treatment problems since pollution laws generally prevent the dumping of raw dyes into municipal water systems and stream, rivers, lakes or the like.
In an effort to more efficiently use dyes, and thereby reduce the waste effluent problem, systems have been developed wherein dyes are first foamed and then applied to the surface of textile materials. The foaming process permits greater control over the amount of dye applied per unit area of the textile material with the object being the use of only so much dye as is actually necessary to dye the material. When the textile material to be dyed is a tufted pile carpet, it is often difficult to obtain uniform application of dye to the pile since it is usually difficult to doctor the foam onto the pile in a uniform layer. Uniform application of the foamed dye is essential to the production of a carpet which is dyed to a uniform color and is free of streaks. In those systems in which foamed dyes have been used, the carpet with the foamed dye thereon is usually fed into a steam chamber for fixation of the dye to the pile fibers. However, in virtually all steam chambers, condensation is extensive and dripping of condensation onto the carpet often produces uneven coloration. Steam chambers require relatively large amounts of energy compared to that actually required for the fixation of the dye on the carpet. Moreover, continuous dyeing processes require that the entry and exit ends of the steam chamber be open to permit introduction and removal of the carpet, thereby resulting in further energy inefficiency.